This invention relates to image processing techniques and tools for manipulating captured images. Image capture devices, such as cameras, can be used to capture an image of a section of a view, such as a section of the front of a house. The section of the view whose image is captured by a camera is known as the field of view of the camera. Adjusting a lens associated with a camera may increase the field of view. However, there is a limit beyond which the field of view of the camera cannot be increased without compromising the quality, or resolution, of the captured image. It is sometimes necessary to capture an image of a view that is larger than can be captured within the field of view of a camera. To do so, multiple overlapping images of segments of the view can be taken and the images can be joined together, or “merged,” to form a composite image, which may sometimes be referred to as a panoramic image.
An image captured by a camera distorts the sizes of objects depicted in the image so that distant objects appear smaller than closer objects. The size distortion, which is known as perspective distortion, depends on the camera position, the pointing angle of the camera, and so forth. Consequently, an object depicted in two different images might not have the same size in the two images, because of perspective distortion.